The objective of this study is the development and evaluation of anti-tumor immunotoxins (IT's) for intraperitoneal therapy of advanced intraperitoneal malignancy. Immunotoxins (monoclonal antibody-ricin A chain conjugates) directed against carcinoembronic antigen and human transferrin receptor will be used. The anti- tumor effects of these IT's will be evaluated in human tumor xenografts established as intraperitoneal tumors in nude mice. Alternate methods of immunotoxin construction will be evaluation, to optimize anti-tumor efficacy in these models. Further enhancement of anti-tumor effect of the IT's will be sought, by the in vivo use of modified forms of the IT potentiator monensin (monensin linoleate, monensin in emulsion, and liposomal monensin.) Augmentation of IT anti-tumor effect by combination with radioimmunotherapy (90 Yttrium antibody or 90 Yttrium-IT) will also be examined. A limited clinical trial of i.p. IT's in refractory intraperitoneal malignancy will be performed. This trial will investigate toxicity and efficacy of i.p. IT's, and the biodistribution of 111 Indium-IT's after i.p. infusion will be determined by external scanning and tissue biopsy. These studies should yield important information regarding development of IT's as clinical anti-cancer agents.